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1
Thimmalapura, Satish Voddina. "Identification and compensation of friction for a dual stage positioning system." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2571.
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Motion control systems are usually designed to track trajectories and/or regulate about a desired point. Most of the other objectives, like minimizing the tracking time or minimizing the energy expended, are secondary which quantify the above described objectives. The control problem in hard disk drives is tracking and seeking the desired tracks. Recent increase in the storage capacity demands higher accuracy of the read/write head. Dual stage actuators as compared to conventional single actuator increases the accuracy of the read/write head in hard disk drives. A scaled up version of the dual stage actuator is considered as the test bed for this thesis. Friction is present in all electromechanical systems.
This thesis deals with modelling of the dual stage actuator test bed. A linear model predicts the behavior of the fine stage. Friction is significant in the coarse stage. Considerable time has been spent to model the coarse stage as a friction based model. Initially, static friction models were considered to model the friction. Dynamic models, which describe friction better when crossing zero velocity were considered. By analyzing several experimental data it was concluded that the friction was dependent on position and velocity as compared to conventional friction models which are dependent on the direction of motion. Static and Coulomb friction were modelled as functions of velocity and position. This model was able to predict the behavior of the coarse stage satisfactorily for various initial conditions. A friction compensation scheme based on the modelled friction is used to linearize the system based on feedback linearization techniques.
2
Wong, Chian Xng. "Nonlinear system identification with emphasis on dry friction." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425213.
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Längkvist, Martin. "Online Identification of Friction Coefficients in an Industrial Robot." Thesis, Linköping University, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-19269.
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All mechanical systems with moving parts are affected by friction, including industrial robots. Being able to design an accurate friction model would further increase the performance of todays robots. Friction is a complex dynamic phenomena that is constantly changing depending on the state and environment of the robot. It is therefore beneficial to update the parameters of the friction model online. An estimate of the friction will be made using the feedback control signal with the help of a feedforward control scheme in a two axis simulation setup. The friction estimate is then used for an offline identification of three friction model parameters in a static Lugre friction model. Improvements on the identification will be done by introducing some shut-off rules that will improve the estimate. The normalized least mean square method (NLMS) will then be used to update the parameters online. A simulation of friction compensation with a fixed friction model, and with an adaptive friction model will be studied. The method will also be simulated using experimental data taken from a real industrial robot.
4
Marshall, Dustin John. "An Alternative System Identification Method for Friction Stir Processing." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4061.
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Temperature control has been implemented in friction stir processing and has demonstrated the ability to give improved process control. In order to have optimal control of the process, the parameters of the system to be controlled must be accurately identified. The system parameters change with tool geometry and materials, workpiece materials, and temperature. This thesis presents the use of the relay feedback test to determine the system parameters. The relay feedback test is easy to use and promotes system stability during its use. The results from the relay feedback test can be used to determine controller gains for a PID controller. The use of this method, as well as the quality of the resulting control is demonstrated in this paper.
5
Elhami, Mohammad Reza. "Modelling, identification and compensation of friction in robot control systems." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243266.
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Khatibi, Rahman Haghi. "Mathematical open channel flow models and identification of their friction parameters." Thesis, University of London, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263145.
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This thesis l concerned with the mathematical modelling of open channel flows governed by the Saint-Venant equations, which are used as a prediction or identification tools. A survey of the literature in these fields identified the problems in need of Immediate research. Numerical test runs were then devised which led to projecting a clear picture as follows. The performance of twn widely used Implicit finite difference schemes, the 4-point box and 6-point staggered schemes were compared In a wide range of circumstances. it is concluded that both schemes produce 'very close results, but the staggered scheme is prone to convergence problems In some extreme cases. It was also noted that a sharp change in geometric configuration of compound channels produced discontinuous features on the aim ulated depth and discharge hydrographs. The inability of the staggered scheme In handling a head-discharge relationship as a downstream boundary condition was tackled by proposing and implementing a scheme of second order accuracy. As model data are generally corrupted withh errors and noise, their effects together with that of other factors on the Identified friction parameters we Investigated. The results demonstte the paramount Importance of the effect of a choice of objective function on the Identified parameters. While the individual values of the identified M2nning n may vary from one flood event to another, their mean is shown both numerically and rigorously to be dependent upon the choice of objective function. It is shown that an objective function formulated by using absolute errors performs ideally and produces reliable results even in the presence of autocorrelated Gaucian noise samples. The mean of the Identified parameters is also found to be adversely affected if the observation station is affected by localized disturbances. Sensitivity of objective functions to the variation In the value of the friction parameter Is also found to be an Important factor, as Insensitivity leads to ill-conditioning.
7
Ren, Ying. "The analysis and identification of friction joint parameters in the dynamic response of structures." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8904.
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Piroti, Shwana, and Jesper Eriksson. "Friction Modeling in FE Simulation : Identification of Friction Model Parameters in Airbag and Crash Dummy Head Contact through Simulation and Experimental Data Response Correlation." Thesis, KTH, Hållfasthetslära (Avd.), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232473.
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Motor vehicle-traffic accidents are a common cause of traumatic brain injuries, resulting in severe and sustaining disabilities, or even fatality. In an effort to mitigate injuries related to vehicle crashes, various safety systems such as the occupant airbag has been implemented. In angled impacts, occupant interaction with the airbags can lead to head rotation, and during recent years head rotation has been emphasized as an important contributor to head injury risk. Therefore, for prediction of head injury risk in crash simulations it is important to correctly model the friction force which arises in the contact between occupants and the car interior. The aim of this thesis is therefore to study the friction within such a system. More specifically, the analysis is focusing on dummy head to airbag interaction and to correlate a three parameter friction model for this contact pair, as well as a one parameter model currently used by Volvo Car Group, with measured laboratory test data in the software LS-DYNA.A preliminary study in LS-DYNA was conducted to determine the configuration of the laboratory setup consisting of a statically inflated customized driver airbag and a crash dummy head being launched to impact the airbag. The laboratory test data was analyzed using linear regression and Students T-test to identify the influence of parameters on the measured responses. The simulation model was then modified to represent the laboratory setup, prior to an optimization study performed to correlate simulation and laboratory test data responses. Lastly, an evaluation study was made to test whether or not the proposed friction model could improve occupant crash simulations.It was found in the thesis study that the friction force had a large effect on the rotation of the head around the vertical axis (z−axis in the anatomical coordinate system of the head). The experimental data showed that the internal pressure of the airbag had little effect on the response. This was likely due to the studied pressures being large enough for the airbag to be so stiff that no plowing effect of the dummy head moving through the airbag fabric could be seen. Furthermore, results from the optimization study indicated that the model correlation was improved when a three parameter friction model with velocity dependence was used. This implies that the friction coefficient is dependent on the velocity. It was also shown that material properties affecting friction behavior vary between different crash dummy heads, as well as different surface coating. Both dummy T-shirt fabric and grease paint resulted in significantly lower surface friction.Due to the difference in friction for different dummy heads, a single set of friction model parameter values that describes the friction behavior of all crash dummy heads does not exist. The study finds that when sliding is present in a contact, a three parameter model for describing the friction improves the correlation, as it can account for the velocity dependence of the friction in the contact. In contrast, when sliding is not present the one parameter and the three parameter model give similar results.Keywords: friction, velocity dependent friction coefficient, finite element analysis, car crash simulation, Volvo Cars, crash test dummy head, driver airbag, LS-DYNA, laboratory testing, optimization study.
9
Wondimu, Nahom Abebe. "SIMULATED AND EXPERIMENTAL SLIDING MODE CONTROL OF A HYDRAULIC POSITIONING SYSTEM." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145419922.
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Cho, Hyunjoong. "Development of advanced techniques for identification of flow stress and friction parameters for metal forming analysis." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1167699938.
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Poudel, Om Prakash. "Identification of barriers and least cost paths for autonomous vehicle navigation using airborne LIDAR data." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/43304.
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In the past several years, the Defense Advanced Research Projects Agency (DARPA) has sponsored two Grand Challenges, races among autonomous ground vehicles in rural environments. These vehicles must follow a course delineated by Global Positioning System waypoints using no human guidance. Airborne LIDAR data and GIS can play a significant role in identifying barriers and least cost paths for such vehicles. Least cost paths minimize the sum of impedance across a surface. Impedance can be measured by steepness of slope, impenetrable barriers such as vegetation and buildings, fence lines and streams, or other factors deemed important to the vehicleâ s success at navigating the terrain. This research aims to provide accurate least cost paths for those vehicles using airborne LIDAR data. The concepts of barrier identification and least cost path generation are reviewed and forty-five least cost paths created with their performance compared to corresponding Euclidean paths. The least cost paths were found superior to the corresponding Euclidean paths in terms of impedance as they avoid barriers, follow roads and pass across relatively gentler slopes.Master of Science
12
Zanhar, Andrej. "Modeling, Identification and Control Design for an Electro-Hydraulic Rotator." Thesis, Linköping University, Department of Electrical Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54377.
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Robotic manipulators have been introduced in industry as a form of increasing productivity. Today, there exist an interest to enlarge the application of these manipulators to outdoor environments. Forestry cranes used in the forestry industry are a clear example. A long term goal in this industry is the development of autonomous systems to increase the logging efficiency. In this thesis, we consider how to control the rotator of these cranes, which is an electro-hydraulically actuated motor, and is used to control the end ffector tool. Control system design for the rotator is a challenging task since the sensing is not available to full extent. The main reason is the harsh environment that these machines are exposed to and sensors such as encoders are very fragile and cannot be used. In this thesis we use alternative sensing devices, such as a magnetic sensor and a stereo camera. In the case of the camera we face a problem with big delay. A prediction method has been used to compute desired values. Due to various reasons certain measuring devices can not be used in the industry. We consider four cases for control system design where dfferent combinations of available sensors have been used. Initially angular position of the rotator is controlled using only the magnetic sensor. A cascade control setup is used where pressure and position are measurable, first using the magnetic sensor and later using the camera. When only pressure measurements are available identified models have replaced sensors for position feedback. All tests and experiments have been done using a scaled version of a real forestry crane. The available crane has similar configuration and dynamics as the real one and is therefor useful for experimental purposes.
13
Niglis, Anton, and Per Öberg. "Modelling High-Fidelity Robot Dynamics." Thesis, Linköpings universitet, Reglerteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119640.
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The field of robotics is in continuous development. Driving forces for the development are higher demands on robot accuracy and being more cost effective in the development process. To reduce costs, product development is moving towards virtual prototyping to enable early analysis and testing. This process demands realistic models and modelling is therefore of utmost importance. In the process of modelling high fidelity robot dynamics many different physical aspects have to be taken into account. Phenomena studied in this thesis stretch from where to introduce flexibilities, mechanical and dynamical coupling effects, and how to describe friction. By using a bottom up approach the effects are analysed individually to evaluate their contribution both to accuracy and computationalcomplexity. A strategy for how to model a flexible parallel linkage manipulator by introducing some crucial simplifications is presented. The elastic parameters are identified using a frequency domain identification algorithm developed in [Wernholt, 2007] and shows that the presented method works well up to a certain level of fidelity. Friction is modelled using empirically derived static and dynamic models. Evaluation of accuracy is conducted through identification of friction models for a real manipulator and it is seen that to capture all existing phenomena in low velocities a dynamic model is needed. It is also seen that friction characteristics vary with temperature and a Kalman filter is suggested to adaptively estimate friction parameters. Finally an implementation of a flexible manipulator model using the software MapleSim is presented. The tool severely simplifies the process of modelling manipulators and enables for export to other environment such as simulation, optimization and control.
14
Durand, Bastien. "Etude expérimentale du frottement entre l’acier et un matériau fragile sous haute vitesse et haute pression." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2039/document.
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L’objectif de la thèse est la caractérisation expérimentale du frottement entre l’acier et un matériau fragile. Les pressions et les vitesses de glissement qu’on cherche à atteindre sont respectivement de l’ordre de 10 à 100 MPa et l’ordre de 10 à 100 m/s. Les tribomètres classiques ne peuvent pas être utilisés car les pressions qu’on cherche à atteindre sont suffisamment élevées pour mener le matériau fragile à rupture. Pour pallier cette difficulté, le matériau doit être confiné. Un échantillon cylindrique du matériau est alors inséré dans un tube en acier qui fait à la fois office de confinement et de surface de frottement. Avec cette configuration, comme nous ne pouvons pas effectuer de mesures directes au niveau de l’interface, les paramètres de frottement sont identifiés à partir de mesures indirectes et de modèles analytique et numérique. Deux types de dispositifs ont été conçus pour effectuer à la fois des essais d’orientation en quasistatique et des essais sur barres de Hopkinson. Les essais quasi-statiques permettent une identification fiable du frottement et montrent que des pressions de 100 MPa peuvent être obtenues avec notre configuration sans dégrader le matériau fragile. En revanche, les essais sur barres de Hopkinson ne donnent pas satisfaction. Un dispositif spécifiquement adapté à la dynamique rapide a alors été conçu. Il permet d’identifier le frottement sous des pressions de 100 MPa et des vitesses de10 m/sThe aim of the thesis is the experimental characterisation of the friction between steel and a brittle material. The desired pressures and the desired sliding velocities are respectively of the order of 10-100 MPa and 10-100 m/s. Usual tribometers cannot be used because the desired pressures are high enough to fracture the brittle material. The material has to be confined to overcome this difficulty. A cylindrical sample of the material is therefore inserted into a steel tube which acts both as a confinement and a sliding surface. Such a configuration does not enable to carry on direct measurements on the interface, the friction parameters are thus identified from indirect measurements and from analytical and numerical models. Two types of set-up have been designed to carry on both quasi-static tests and tests on split Hopkinson pressure bars. Quasi-static tests enable a reliable identification of friction and show that the desired pressures can be reached with our configuration whilst retaining the brittle material integrity. Unfortunately, the results obtained with split Hopkinson pressure bars are not satisfactory. A set-up specifically adapted to dynamic situations has thus been designed. It enables identification of friction under pressure of 100 MPa and velocities of 10 m/s
15
Borsotto, Bastien. "Modélisation, Identification et commande d'un organe de friction Application au contrôle d'un système d'embrayage et au filtrage d'acyclismes par glissement piloté." Phd thesis, Université Paris Sud - Paris XI, 2008. http://tel.archives-ouvertes.fr/tel-00350533.
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Dans un moteur thermique, les explosions dans les différents cylindres engendrent un couple moteur entaché de composantes harmoniques communément désignées par le terme d'acyclismes. A faible régime, la propagation de ces composantes à travers la chaîne cinématique du véhicule (embrayage, boîte de vitesse, transmission), peut être à l'origine de nombreuses nuisances vibro-acoustiques. Pour limiter ces nuisances, un filtrage de ces composantes est envisagé en utilisant le système d'embrayage, par la maîtrise du glissement relatif des disques le constituant : c'est le glissement piloté. Afin de commander le système d'embrayage en conséquence, il est important d'en définir un modèle de comportement précis, s'appuyant sur la description des phénomènes de frottement. Les caractéristiques des principaux modèles de frottement issus de la littérature, ainsi que les méthodes d'identification de leurs paramètres et les conditions d'essais associés, ont ainsi été étudiées. L'élaboration d'un banc autorisant la caractérisation de matériaux de friction, a ensuite été développée. Les essais expérimentaux réalisés à partir de celui-ci, ont alors permis de recaler les modèles de frottement retenus, sur le comportement particulier des disques d'embrayage utilisés sur véhicules. Enfin, sur la base du modèle d'embrayage ainsi obtenu, une structure de commande simple a été synthétisée selon une approche en plusieurs étapes : détermination de la structure générale adaptée au problème, réglage du correcteur, analyse des propriétés de robustesse du système bouclé, et retouche des réglages. Les performances de la solution de pilotage proposée sont enfin validées sur un modèle de simulation, puis sur véhicule.
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Borsotto, Bastien. "Modélisation, identification et commande d’un organe de friction : application au contrôle d’un système d’embrayage et au filtrage d’acyclismes par glissement piloté." Paris 11, 2008. http://www.theses.fr/2008PA112062.
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Dans un moteur thermique, les explosions dans les différents cylindres engendrent un couple moteur entaché de composantes harmoniques communément désignées par le terme d’acyclismes. A faible régime, la propagation de ces composantes à travers la chaîne cinématique d’un véhicule (embrayage, boîte de vitesses, transmission), peut être à l’origine de nombreuses nuisances vibro-acoustiques. Pour limiter ces nuisances, un filtrage de ces composantes est envisagé en utilisant le système d’embrayage, par la maitrise du glissement relatif des disques le constituant : c’est le glissement piloté. Afin de commander le système d’embrayage en conséquence, il est important d’en définir un modèle de comportement précis, s’appuyant sur la description des phénomènes de frottement. Les caractéristiques des principaux modèles de frottement issus de la littérature, ainsi que les méthodes d’identification de leurs paramètres et les conditions d’essais associés, ont ainsi été étudiées. L’élaboration d’un banc autorisant la caractérisation de matériaux de friction, a ensuite été lancée. Les essais expérimentaux réalisés à partir de celui-ci, ont alors permis de recaler les modèles de frottement retenus, sur le comportement particulier des disques d’embrayage utilisés sur véhicules. Enfin, sur la base du modèle d’embrayage ainsi obtenu, une structure de commande simple a été synthétisée selon une approche en plusieurs étapes : détermination de la structure générale adaptée au problème, réglage du correcteur, analyse des propriétés de robustesse du système bouclé, et retuning. Les performances de la solution de pilotage proposée sont enfin validées sur un modèle de simulation, puis sur véhiculeIn an internal combustion engine, cylinders explosions create an engine torque chattered by harmonic components called acyclic phenomena. For low velocities, the propagation of these harmonic components across the vehicle kinematics chain (clutch, gearbox, transmission) can introduce vibro-acoustical nuisances. To reject them, a filtering method is considered using the clutch system, by controlling the disks relative behaviour in slipping phases. This idea is “sliding control”. To control the clutch system in such a way, it is important to get a fine model of its behaviour, starting from friction phenomena properties. Thus, the main friction models, as well as parameters identification methods and their related experimental conditions, have been studied. A mechanical benchmark, allowing friction material characterization, has been built. Experimental measurements have led to friction models matching the specific behaviour of the clutch disks used on vehicles. Finally, based on the designed clutch model, the control structure is synthesized following a multi-stage approach: determination of the general structure well suited to the problem, fine regulator tuning, robustness analysis of the closed loop system, and retuning of the control law if necessary. Performances offered by the sliding control solution are finally much than satisfactory in simulation as well as for real tests on vehicle
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Soule, de lafont Marie-France. "Conception d’un connecteur élément fini pour la simulation des assemblages boulonnés." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN021/document.
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Le dimensionnement des liaisons boulonnées représente une part non négligeable du travail des bureaux d’études des industries aéronautiques. En effet leur nombre peut varier de plusieurs milliers à plusieurs millions selon le type d’avion. À l’heure actuelle la mise au point de ce type d’attache se fait grâce à des éléments finis en trois dimensions. La complexité des phénomènes mis en jeux par ce type de connexion tels que le contact le frottement et les jeux entraînent des calculs non linéaires très chronophages.L’objectif des travaux de thèse a été de proposer un connecteur élément fini remplaçant l’ensemble de la discrétisation 3D d’un boulon pour les calculs numériques de dimensionnement en étant basé sur des paramètres liés au comportement mécanique.La mise au point d’un algorithme prenant en compte le contact afin de modéliser le comportement global des parties assemblées fut le point de départ de la réflexion.Cet algorithme a été implémenté au sein du logiciel Samcef à travers une routine codée en Fortran 77.Des tests de qualifications du comportement normal et tangentiel ont été effectués afin de valider l’algorithme mis au point.Une méthode d’identification des paramètres du connecteur est ici proposée : certains peuvent être déterminés de manière analytique et d’autres de manière numérique.Enfin des cas tests de validation sur des assemblages industriels ont été effectués afin de mettre en évidence un gain en temps de calcul conséquent tout en maintenant une qualité suffisante pour le dimensionnementThe design of bolted connections represents a significant part of the work of research department of aeronautical industries. Indeed, their number can vary from several thousands to several millions depending on the aircraft type. At the present time, the development of this type of attachment is done with finite elements in three dimensions. The complexity of concerned phenomena by this type of connection as the contact friction and gaps requires nonlinear computations which are very time consuming.The aim of the thesis was to propose a finite element connector for replacing the whole 3D discretisation of a bolt during the design computations while being based on parameters related to mechanical behaviour.The development of an algorithm taking into account contacts to model the overall behaviour of the parts was the starting point of the reflexion.Then this algorithm was implemented in the SAMCEF software through a routine coded in Fortran 77.Normal and tangential behaviour qualification tests were performed to validate the algorithm developed.A method for identifying connector parameters is proposed here, some of these parameters can be determined using an analytical approach, others need a numerical one.Finally, validations on industrial test cases were carried out to prove a substantial cpu time savings while maintaining a good level of quality
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Yumer, Mehmet Ersin. "On The Non-linear Vibration And Mistuning Identification Of Bladed Disks." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611498/index.pdf.
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Forced response analysis of bladed disk assemblies plays a vital role in rotor blade design and has been drawing a great deal of attention both from research community and engine industry for more than half a century. However because of the phenomenon called &lsquomistuning&rsquo
, which destroys the cyclic symmetry of a rotor, there have been several difficulties related to forced response analysis ever since, two of which are addressed in this thesis: efficient non-linear forced response analysis of mistuned bladed disks and mistuning identification. On the nonlinear analysis side, a new solution approach is proposed studying the combined effect of non-linearity and mistuning, which is relatively recent in this research area and generally conducted with methods whose convergence and accuracy depend highly on the number of degrees of freedom where non-linear elements are attached. The proposed approach predicts nonlinear forced response of mistuned bladed disk assemblies considering any type of nonlinearity. In this thesis, special attention is given to the friction contact modeling of bladed disks which is the most common type of nonlinearity found in bladed disk assemblies. In the modeling of frictional contact a friction element which enables normal load variation and separation of the contact interface in three-dimensional space is utilized. Moreover, the analysis is carried out in modal domain where the differential equations of motions are converted to a set of non-linear algebraic equations using harmonic balance method and modal superposition technique. Thus, the number of non-linear equations to be solved is independent of the number of non-linear elements used. On the mistuning identification side, a new method is enclosed herein which makes use of neural networks to assess unknown mistuning parameters of a given bladed disk assembly from its assembly modes, thus being suitable for integrally bladed disks. The method assumes that a tuned mathematical model of the rotor under consideration is readily available, which is always the case for today&rsquo
s realistic bladed disk assemblies. A data set of selected mode shapes and natural frequencies is created by a number of simulations performed by mistuning the tuned mathematical model randomly. A neural network created by considering the number of modes, is then trained with this data set for being used to identify mistuning of the rotor from measured data. On top of these, a new adaptive algorithm is developed for harmonic balance method, several intentional mistuning patterns are investigated via excessive Monte-Carlo simulations and a new approach to locate, classify and parametrically identify structural non-linearities is introduced.
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Romano, Rodrigo Alvite. "Identificação de processos não-lineares e quantificação de atrito em válvulas de controle." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-11082010-161706/.
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O atrito em válvulas e a sintonia inadequada de controladores são duas das maiores causas de degradação no desempenho das malhas de controle que incluem tais dispositivos. Assim como modelos de atrito são necessários para diagnosticar o mau funcionamento das válvulas ou para compensar os efeitos indesejáveis causados pelo atrito, modelos de processos são de fundamental importância para o projeto de controladores. Este trabalho estende métodos existentes para estimar parâmetros de modelos de atrito e processo, de modo que uma estrutura não-linear é adotada para representar o processo. O procedimento é baseado em dados de operação em malha fechada. Os algoritmos de estimação desenvolvidos são testados com dados simulados e gerados por uma plataforma híbrida (composta por uma válvula real e por uma planta simulada de neutralização de pH), a partir da qual avaliam-se as influências de perturbações, da magnitude do sinal de teste e da sintonia do controlador nos modelos estimados. Os resultados demonstram que o nível de atrito é corretamente quantificado, assim como bons modelos para o processo são estimados em diversas situações. Além disso, a extensão proposta apresenta vantagens significativas em relação a outros métodos, como: (1) maior exatidão na quantificação do nível de atrito, principalmente para processos em que as não-lineares sejam mais severas e (2) estimativas razoáveis do comportamento estático não-linear.The friction in control valves and inadequate controller tuning are two of the major sources of performance degradation in control loops that include such devices. As friction models are needed to diagnose abnormal valve operation or to compensate such undesirable effects, process models play an essential role in controller design. This work extends existing methods that jointly identify the friction and process model parameters, so that a nonlinear structure is adopted to represent the process model. The procedure is based on data from closed-loop experiments. The developed estimation algorithms are tested with data from simulations and generated by a hybrid setup (composed of a real valve and a simulated pH neutralization process), in which the influences of the process disturbances, of the excitation signal magnitude and of the controller tuning on estimated models are investigated. The results demonstrate that the friction is accurately quantified, as well as good process models are estimated in several situations. In addition, the proposed extension presents significant advantages in relation to other methods, such as: (1) greater accuracy for friction quantification, especially for highly nonlinear processes and (2) reasonable estimates of the nonlinear steady state characteristics.
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Wang, Ke. "Modélisation d'un robot manipulateur en vue de la commande robuste en force utilisé en soudage FSW." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0003/document.
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Le travail présenté dans cette thèse concerne la modélisation et la commande robuste en force de robots manipulateurs industriels à articulations flexibles utilisés pour le procédé FSW. Afin de réduire les temps de calcul et l'occupation de la mémoire, une approche basée sur la méthode par intervalle est proposée en vue de la simplification des modèles dynamiques des robots industriels, et contribue à identifier les paramètres d'inertie qui sont négligeables. Des études de cas sur trois types de trajectoires de test et l’analyse des couples moteurs ont démontré l'efficacité et les bonnes performances de la méthode de simplification. Ensuite, la modélisation dynamique et l'identification des paramètres du procédé FSW ont été effectuées. Les paramètres des modèles linéaires et non-linéaires de forces axiales sont identifiés. Sur la base de la modélisation du procédé FSW qui considère simultanément la cinématique du système complet, le modèle de déplacement du robot rigide, les flexibilités des articulations et le modèle dynamique de la force axiale, un contrôleur robuste en force est obtenu par la méthode de réglage fréquentielle. En outre, un simulateur du procédé FSW robotique est développé et les résultats de simulation montrent les bonnes performances du contrôleur en force. L'oscillation de la force axiale dans le procédé FSW peut être simulée en utilisant un modèle de perturbation de la position verticale de référenceThe work presented in this thesis focuses on the modeling and robust force control of flexible joints industrial robot manipulators used for FSW process. In order to reduce computation time and memory occupation, a novel interval-based approach for dynamic model simplification of industrial robots is proposed, which applies to arbitrary trajectories of whole robot workspace and contributes to obtaining negligible inertia parameters. Cases studies have been carried out on three kinds of test trajectories and torques analysis of robot dynamic equation, demonstrating the effectiveness and good performance of the simplification method. Then, the dynamic modeling and identification of robotic FSW process is performed, and the parameters of linear and nonlinear dynamic axial force process models are identified by using the plunge depth and its derivative. On the basis of the modeling of robotic FSW process which simultaneously considers the complete kinematics, the rigid robot displacement model, the joint flexibility and the dynamic axial force process model, a robust force controller can be obtained by using the frequency response approach. Besides, a simulator of robotic FSW process is developed and simulation results show good performance of the force controller. The oscillation of axial force in FSW process can be simulated when a disturbance model of initial vertical reference position is proposed and used in the simulation
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Rodriguez, Freddy Alexander Murillo. "Avaliação dinâmica de amortecedores por atrito seco para atenuar vibrações de um sistema vibratório." Universidade Federal de Uberlândia, 2014. https://repositorio.ufu.br/handle/123456789/14951.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorIn the present work the effect of a dry friction damper device on the dynamic behavior of vibratory systems is analyzed. Two friction devices are designed consisting of a sphere in contact with a flat steel bar. In the first prototype the normal force on the contact is kept constant. In the second device a piezoelectric actuator is used to vary the intensity of the normal force. An experimental methodology is developed to analyze the dynamic behavior of a vibratory system and to identify the physical properties of the friction damper devices. The mathematical-computational models of the two friction dampers are used to perform simulations with a vibratory system, in order to analyze the influence of the variation of the normal contact force on the behavior of the vibratory system and to evaluate the dissipation of vibrational energy. In the first damper, an experimental methodology is used to identify the behavior of friction force induced on the vibratory system, and also to identify nonlinearities due to friction Frequency response is used to identify the structural frequencies generated by the device, as well the operational band of the damper device with constant normal force. The time domain vibratory system response is used to identify the Coulomb friction model. The second damper is designed by finite element method. Experimental analysis of the device is applied to identify the parameters that define the static and dynamic behavior of the damper with variable normal load, The frequency response is used to identify the structural frequencies generated by the device, as well it s effective operational band.. Another experiment evaluates the effect of the normal contact force variation on the dynamic response of a vibratory structure. The vibratory system response is identified using Coulomb friction models. Finally, numerical simulations are used to evaluate the effect of the normal contact variation, generated by a semi active control, on the vibratory system dynamic behavior. The vibration attenuation and the power demand of the piezoelectric actuator .are evaluated.
Neste trabalho é analisado o efeito de amortecedores de atrito seco sobre o comportamento dinâmico de um sistema vibratório de um grau de liberdade São projetados dois dispositivos de atrito constituídos por uma esfera em contato com um barra plana de aço. No primeiro protótipo a força normal no contato é mantida constante. No segundo dispositivo é utilizado um atuador piezelétrico para variar a intensidade da força normal. É desenvolvida uma metodologia experimental para analisar o comportamento dinâmico do sistema vibratório e identificar as propriedades físicas dos amortecedores de atrito. Os modelos matemáticos-computacionais dos dois amortecedores de atrito são usados para realizar simulações com um sistema vibratório, com a finalidade de analisar a influência da variação da força normal de contato sobre o comportamento do sistema vibratório e avaliar a capacidade de dissipação da energia vibratória. No primeiro amortecedor mediante uma metodologia experimental, é possível identificar o comportamento da força de atrito induzida ao sistema dinâmico, são identificadas também as não linearidades devidas ao atrito. Na resposta em frequência é possível identificar as frequências estruturais geradas pelo dispositivo, assim como a banda de atuação do amortecedor de força normal constante. Por ultimo é identificada a resposta do sistema dinâmico no domínio do tempo, mediante os modelos Coulomb do atrito. Para o segundo amortecedor é apresentado a analise estática dos elementos constituintes via um estudo em elementos finitos. Métodos de analise experimental aplicados para identificar os parâmetros que determinam o comportamento estático e dinâmico do amortecedor de carga normal variável. Na resposta em frequência é possível identificar as frequências estruturais geradas pelo dispositivo, assim como também, a banda de atuação do amortecedor de força normal variável. Em uma segunda fase experimental, avaliam-se os efeitos da variação da força normal no contato, na resposta dinâmica da estrutura vibratória e determina-se o comportamento da força do amortecedor, assim como também se identifica a resposta do sistema, com os modelos de atrito de Coulomb. Finalmente, é avaliada numericamente o efeito do ajuste da força normal do contato, mediante um controle semiativo., Verifica-se a eficiência do controle sobre a vibração da estrutura .e sobre o consumo de potência do atuador piezelétrico.
Mestre em Engenharia Mecânica
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Jousset, Solène. "Vers l'assimilation de données estimées par radar Haute Fréquence en mer macrotidale." Thesis, Brest, 2016. http://www.theses.fr/2016BRES0029/document.
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La Mer d’Iroise est observée depuis 2006, par des radars à haute fréquence (HF) qui estiment les courants de surface. Ces mesures ont une finesse temporelle et spatiale pour permettre de capturer la dynamique fine du domaine côtier. Ce travail de thèse vise à la conception et l’application d’une méthode d’assimilation de ces données dans un modèle numérique réaliste pour optimiser le frottement sur le fond et corriger l’état du modèle afin de mieux représenter la circulation résiduelle de marée et les positions des fronts d’Ouessant en mer d’Iroise. La méthode d’assimilation de données utilisée est le Filtre de Kalman d’Ensemble dont l’originalité est l’utilisation d’une modélisation stochastique pour estimer l’erreur du modèle. Premièrement, des simulations d’ensemble ont été réalisées à partir de la perturbation de différents paramètres du modèle considérés comme sources d’erreur : le forçage météo, la rugosité de fond, la fermeture turbulente horizontale et la rugosité de surface. Ces ensembles ont été explorés en termes de dispersion et de corrélation d’ensemble. Un Lisseur de Kalman d’Ensemble a ensuite été utilisé pour optimiser la rugosité de fond (z0) à partir des données de courant de surface et d’un ensemble modèle réalisé à partir d’un z0 perturbé et spatialisé. La méthode a d’abord été testée en expérience jumelle puis avec des observations réelles. Les cartes du paramètre z0, optimisés, réalisées avec des observations réelles, ont ensuite été utilisées dans le modèle sur une autre période et les résultats ont été comparés avec des observations sur la zone. Enfin, des expériences jumelles ont été mises en place pour corriger l’état modèle. Deux méthodes ont été comparées, une prenant en compte la basse fréquence en filtrant la marée des données et du modèle pour réaliser l’analyse ; l’autre prenant en compte tout le signal. Avec ces expériences, on a tenté d’évaluer la capacité du filtre à contrôler à la fois la partie observée du vecteur d’état (courant de surface) et la partie non-observée du système (température de surface)The Iroise Sea has been observed since 2006 by High Frequency (HF) radars, which estimate surface currents. These measurements offer high resolution and high frequency to capture the dynamics of the coastal domain. This thesis aims at designing and applying a method of assimilation of these data in a realistic numerical model to optimize the bottom friction and to correct the model state in order to improve the representation of the residual tidal circulation and the positions of the Ushant fronts in the Iroise Sea. The method of data assimilation used is the Ensemble Kalman Filter. The originality of this method is the use of a stochastic modeling to estimate the model error. First, ensemble simulations were carried out from the perturbation of various model parameters which are the model error sources: meteorological forcing, bottom friction, horizontal turbulent closure and surface roughness. These ensembles have been explored in terms of dispersion and correlation. An Ensemble Kalman smoother was used to optimize the bottom friction (z0) from the surface current data and from an ensemble produced from a perturbed and spatialized z0. The method is tested with a twin experiment and then with real observations. The optimized maps of parameter z0, produced with the real currents, were used in the model over another period and the results were compared with independent observations. Finally, twin experiments were conducted to test the model state correction. Two approaches were compared; first, only the low frequency, by filtering the tide in the data and in the model, is used to perform the analysis. The other approach takes the whole signal into account. With these experiments, we assess the filter's ability to control both the observed part of the state vector (currents) and the unobserved part of the system (Sea surface Temperature)
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Veselý, Antonín. "Návrh řídicího algoritmu pro elektromechanický aktuátor s výrazným suchým třením." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232062.
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This work deals with identification of systems with high dry friction and/or return spring. Identified models are optimised by Parameter Estimation toolbox. Because friction and return spring have negative influence in control systems, models are used as compensators in control loop. Also effect of parameters variation is investigated in this paper.
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Courbon, Cédric. "Vers une modélisation physique de la coupe des aciers spéciaux : intégration du comportement métallurgique et des phénomènes tribologiques et thermiques aux interfaces." Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00713527.
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De nos jours, le contexte de mondialisation des marchés impose aux industriels des contraintes économiques sans précédent. Afin de rester concurrentiels, ils n'ont d'autre choix que de modifier leur façon de concevoir et d'innover. Les techniques de production sont directement concernées avec par exemple une volonté de réduire les cycles de mise au point visant à définir les paramètres optimaux de mise en forme. On constate alors l'immersion d'un besoin fort en moyens de support, flexibles et prédictifs, permettant de limiter les campagnes d'essais et de faciliter leur exploitation. La simulation numérique se présente comme un outil pouvant répondre à ces critères. Ce travail s'est inscrit dans une démarche d'amélioration de la modélisation et de la simulation des opérations d'usinage, et à une échelle plus locale, de la modélisation de la coupe des métaux. Il aborde donc un problème complexe, fortement couplé, faisant intervenir mécanique, thermique, tribologie et métallurgie dans des conditions extrêmes. Une première partie expérimentale s'est donc orientée vers une compréhension plus fine des mécanismes de coupe mis en jeu en usinage d'un C45 normalisé et d'un 42CrMo4 trempé revenu. Elle a notamment permis de mettre en évidence, dans les zones de déformation intense, des affinements de grain conséquents, produits par l'activation d'un processus de recristallisation dynamique (DRX). L'inspection des zones de contact outil-matière a également montré les fortes hétérogénéités de contact existantes à l'interface outil-copeau et révélant la formation d'une résistance thermique de contact. Une étude rhéologique des deux nuances s'est appuyée sur des essais de compression dynamique. Menée à haute déformation, elle a permis de reproduire les évolutions microstructurales observées en coupe et d'appréhender leur influence sur la limite d'écoulement des matériaux. Deux modèles de comportement "à base métallurgique" ont été identifiés, présentant une retranscription plus fidèle que les modèles phénoménologiques standards. Des essais tribologiques dédiés ont permis d'extraire des modèles de contact capables de reproduire les phénomènes locaux existants à l'interface outil-matière. L'accent s'est principalement porté sur la thermique de contact au travers de lois de partage variables intégrant la notion de résistance thermique. L'intégralité de ces modèles a enfin été implémentée dans le code de calcul Abaqus© grâce à des développements spécifiques. Une stratégie de modélisation a été mise en place autour d'un modèle de coupe 2D afin de restituer les tendances majeures observées lors de la coupe d'aciers spéciaux. L'association de modèles 2D et 3D à copeau continu, de modèles à copeau segmenté ainsi que de simulations thermiques découplées présente un fort potentiel permettant, à terme, de modéliser une opération d'usinage dans sa globalité.
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Makkar, Charu. "Nonlinear modeling, identification and compensation for frictional disturbances." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0014262.
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Kopečný, Lukáš. "McKibbenův pneumatický sval - modelování a použití v hmatovém rozhraní." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233458.
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This work describes exceptional properties of McKibben pneumatical muscle and introduces its state-of-the-art model. The mathematical model is extended especially in a field of a thermodymical behavior. A new model applies a method used for describing of a thermodynamical behavior of pneumatic cylinders until now. This method is significantly upgraded to fit a muscle behavior, particularly by considering a heat generated by a muscle internal natural friction. The model is than verified and discussed with a real system. The haptic part introduces a development and design of a haptic glove interface for the use in robotics, especially in telepresence, or in VR. The force and touch feedback is provided by Pneumatic Muscles controlled by an open loop algorithm using the introduced mathematical model. The design is light and compact.
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Rua, Sandra Cristina Camacho Gomes. "Essays in macroeconomics with general equilibrium models." Doctoral thesis, Instituto Superior de Economia e Gestão, 2014. http://hdl.handle.net/10400.5/7543.
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Doutoramento em EconomiaModelos de equilíbrio geral são largamente usados na academia e em instituições internacionais. Aqui, questões relacionadas com reformas estruturais, o limite inferior das taxas de juro e sua relação com opções de política são analisadas com um modelo de larga escala. Os principais resultados são: reformas estruturais unilaterais são benéficas e coordenação nacional tem vantagens; com as taxas de juro no limite inferior, políticas orçamentais e estruturais podem aliviar uma recessão e reduzir o tempo em que esse limite é activo. Mas a eficácia depende do instrumento orçamental e das características das reformas. Seguidamente, modelos estimados de media-escala são usados para avaliar a importância de choques antecipados nos EUA. Primeiro, avalia-se o papel destes choques na dinâmica do mercado habitacional e conclui-se que são importantes nas flutuações deste mercado e em particular nos ciclos de boom-bust. Expectativas de inquéritos sao usadas como validação externa do modelo. Depois, o papel de choques antecipados de politica monetária e analisado num modelo de ciclo económico. Conclui-se que melhoram a desempenho do modelo sem causar problemas de identificação; explicam uma percentagem maior das flutuações das variáveis observadas que choques não antecipados de politica monetária; e ajudam a melhor replicar covariâncias de algumas variáveis.
General equilibrium models are widely used in academia and policy institutions. Here, issues related to structural reforms, the zero lower bound and its interaction with policy options are analysed with a large-scale calibrated model of the euro area. The main find- ings are: unilateral structural reforms are beneficial and cross-country coordination has advantages; at the zero bound, fiscal and structural policies can alleviate a recession and reduce the time spent at the bound but their effectiveness depends on the fiscal instrument and the design of the reforms. Then, medium-scale estimated models are used to assess the importance of news shocks in the US. First, the role of news in housing market dynamics is investigated. Results show that news shocks are important for housing market fiuctua- tions, and in particular boom-busts cycles. Survey-based expectations are used as external validation of the model. Then, the role of monetary policy news shocks is analysed in a business cycle model. Results show they improve the performance of the model without leading to identification problems; they account for a larger fraction of the fiuctuations in observables than the unanticipated monetary policy shock; and they help to achieve a better matching of the covariances of some observables.
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Jung, Meng Liang, and 鍾孟良. "Experimental Study on Friction Model Identification and Feedforward Compensation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/9gwp3b.
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碩士國立臺北科技大學
機電整合研究所
99
Experimental study on friction model identification and feedforward compensation.The characteristics of static friction in a mechanical system are investigated through the construction of friction compensation lookup tables based on slow-velocity friction experiments in order to develop improved friction models for computer numerical control (CNC) machining. Friction in the feed drive servomechanisms of CNC milling machines can degrade the accuracy of tool motion. Although friction compensation has been applied with good results in CNC tool motion control, the simplified model of friction used for such schemes limits the ultimate motion accuracy of feed drives. As an alternative to the time-consuming and tedious breakaway experiments that are generally used to identify static friction in a mechanical system, an experimental methodology based on slow-velocity measurements and a friction compensation lookup table is proposed. Analysis of the measured friction using a spatial fast Fourier transformation algorithm shows the feasibility of the experiments for constructing accurate friction models. Integration of the friction compensation lookup table with a velocity-dependent friction model reduces the adverse effects induced by both static and velocity-dependent friction. On this basis, an integrated friction model that considers the position dependence of friction developed for friction compensation, and a feedforward friction compensation structure is presented for the control of motion in mechanical systems. Experiments and motion tests using an axial servomechanism illustrate the feasibility of the proposed friction compensation method.
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Turhan, Mustafa Hakan. "System Identification and Adaptive Compensation of Friction in Manufacturing Automation Systems." Thesis, 2013. http://hdl.handle.net/10012/7901.
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Industrial demands for more efficient machine tool systems have been significantly increased. In order to obtain high performance machine tool systems, researchers are focused on enhancing functioning of various components of machine tool systems. Feed drives are important component of the most of machine tool systems such as computer numerical control (CNC) machines for achieving desirable performance. An essential research stream of current interest aiming enhancement of feed drive performance is construction of control methods that help to decrease tool positioning errors in the system. An effective approach for mitigation or reduction of positioning errors is modeling, identifying, and compensating friction in appropriate manner. In addition, accurate modeling of feed drive systems is essential in elimination of these positioning errors. In this thesis, the precision control of feed drives is studied using several different control methods. Firstly, the feed drive type that has common use in machine tools is chosen to be main focus for this research, namely ball screw drive. Different dynamic models of ball screw drive are shown in detail. In addition, some of the nonlinearities that affect ball screw dynamics such as friction affects are discussed. Friction modeling needs to be performed realistically and accurately in order to design an effective compensator to cancel friction effects. In general, the friction models are divided into two categories; classic (static) and dynamic friction models. In this thesis, we present details of these models and derive linear parametrization of the key ones. Based on the derived linear parametric models, we design a least-squares on-line friction estimator and adaptive friction compensation scheme. The performance of these designs are verified via simulation and real-time experimental tests. Noting that the parameters of the base rigid body model, i.e., inertia and viscosity constants, need to be known precisely for effective high precision control tasks, including the aforementioned adaptive schemes. The second part of the thesis focuses on off-line identification of these key base model parameters. In this part, we present a real-life case study on identification of plant and built-in controller parameters and a simulator design based on this identification for a grinding CNC machine used in a gear manufacturing company.
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Johnson, Craig T. "Identification of friction and its compensation in precise, position controlled systems." 1992. http://catalog.hathitrust.org/api/volumes/oclc/32282553.html.
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Thesis (MS)--University of Wisconsin--Madison, 1992.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 139-141).
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Che-WeiChen and 陳哲葦. "System Identification and Control for Moving Small Objects with Dry Friction." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/45027060099505243056.
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碩士國立成功大學
機械工程學系
102
The objective of this thesis is to establish an equipment that can measure friction coefficients between moving small objects and experimental platform for identifying a dynamic friction model and examine the friction model in a one-dimensional pushing control and positioning system. Coulomb and Karnopp model are applied in modeling the friction of moving small objects in one-dimensional motion. The inverse Preisach compensation of piezoelectric actuator is implemented by utilizing neural network method for driving test platform. The experimental tests are analyzed for friction coefficients of rectangular and cylindrical small objects with different materials relative to glass vibration platform. In addition, the influence of surface roughness on friction coefficient is considered. With the actual and simulated response of displacement, a genetic evolutionary algorithm is employed for estimating friction parameters in system identification. Finally, the estimated friction model is applied to a one-dimensional dynamic control system. A closed-loop controller is designed and implemented to achieve pushing and positioning of small objects and the system stability is analyzed.
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Chang, Wei Chi, and 張韋棋. "Identification of system with friction and model parameters on multi-axis platform." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/57509818581109055139.
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碩士清雲科技大學
機械工程研究所
94
The multi-axis platform is a common mechanism in the servo mechanisms. Friction is an inevitable physical phenomenon present in mechanisms which produces undesirable behaviors in control systems such as position and tracking errors, and limit cycles. It also involves static, viscous, coulomb friction etc. The effects of system with friction are considered by the multi-axis platform. Then we develop a general estimation method for the identification of equivalent inertia and damping of systems with friction. Furthermore, the first and second order characteristics are going to be considered to estimate the parameters respectively by the experiment.
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Liu, Chung-Ching, and 劉崇慶. "Identification of Friction Parameters and Dynamic Analysis of the Feed Drive System." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/49w8t9.
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碩士國立中正大學
機械工程學系暨研究所
101
In order to create a feed drive platform which operates at a higher level of precision, it is necessary to identify its rotational inertia and friction parameters and then design its motion controller and friction compensator. This thesis will focus on three topics in this area of research. Firstly, the proposal of a new friction identification method. This method is called Short Time Identification Method of Friction (STIMOF), it allows the identification of the feed drive system of its friction parameters and inertia to be obtained within 10 seconds with a movement stroke length of 100mm. Secondly, the velocity controller, position controller and velocity feed-forward controller is designed using the results obtained from using STIMOF. Thirdly, the proposal of two kinds of compensation methods, Torque Command Compensation (TCC) and Quadrant Error Compensation (QEC). By using computer simulations, it has been confirmed that both these methods can indeed reduce velocity error of the feed drive platform by inversing the velocity.
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Shih, Yu Chung, and 施予中. "Modeling and Identification of PWM Driving and Friction Effects for DC Motors." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/15477266064087184377.
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碩士國立臺灣科技大學
機械工程系
101
Motors are almost everywhere in our daily life. It’s important to research how to control the industrial motors precisely and more efficiently. This paper focuses on the goal to identify the non-linear physical features of brushed DC motors by using the MATLAB to simulate the dynamic model. During the experiments, different kinds of friction and friction effects are considered while the motors work under the load. The models identified include PWM (Pulse Width Modulator), the friction effects generated by the load of gear box load, and the delay effects produced by the transistor current dissipation during deceleration process. In addition to coulomb friction and viscous friction, the Stribeck friction effect which is generated under very low speed is considered. The friction model is applicable even when the motors’ speed down to very low speed. This paper also has general equations to describe the velocity response during the deceleration. The PWM motor driver used to control the motor speed in this thesis offers two modes in the deceleration process, including Coast and Brake. This thesis focuses on the current release effect during the Coast mode and developed a model that can identify the effect.
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Chiu, Chun-Ming, and 邱俊明. "The Friction Model Identification and Control Compensation of a Piezoelectric Actuated Positioning Table." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/2x8zjd.
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碩士國立臺灣科技大學
機械工程系
95
In this paper, the friction model of an X-Y table actuated by linear-piezoelectric motors is investigated. This positioning table has slowly nonlinear friction properties, especially at slow motion phase. Firstly , Genetic Algorithm is employed to estimate the parameters of a LuGre friction model. Secondly , a model-based adaptive sliding mode controller was developed based upon the estimated model and a back-stepping adaptive sliding controller with unknown model parameter was designed. The first controller, orthogonal series function is employed to approximate the unknown disturbance terms of the friction model. Then the adaptive sliding mode controller is designed based on the GA estimated model and function at uncertainly. Since the coefficients of the function approximation are time –invariant, control strategies and updated laws can be easily derived from Lyapunov approach to guarantee the boundaries of output signals. The second controller, a back-stepping method is adopted to design an adaptive sliding control based on design the unknown parameters update law of friction model.
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Tang, Wei-yu, and 湯惟宇. "The Development of a Self-Tuning Motor Controller with On-Line Parameter Identification and Automatic Off-Line Static Friction Identification." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/92079820712127149051.
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碩士國立成功大學
航空太空工程學系碩博士班
97
For static friction identification, from Hsieh and Pan[1], there is a nonlinear spring in the static friction phase. So, use the equation that is represented by Hsieh and Pan[1] to fit the nonlinear spring curve via binary method. For on-line identification, Use estimated output and actual output to get error, and use gradient search method with weighting and gradient search method without weighting to improve the motor parameters. If the motor parameters change or the intial motor parameters are wrong, we will find and use on-line identification to decrease the error between the actual parameters and the estimated parameters. With simulation and experiments, verify the above method.
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Jelínek, Milan. "Daktyloskopie - historie, současnost a budoucnost." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-334422.
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Dactylography - History, Present and Future This thesis introduces one of the most important identification methods - dactylography (or dactyloscopy), e.g. the method based on analysis and classification of patterns of friction ridges (especially fingerprints). This thesis consists of three main chapters considering its name. The first chapter describes interesting history of this method from first discoveries, through various breakthroughs, to reaching the status of forensic evidence. This chapter mainly focuses on individual pioneers on the field of dactylography, but tells as well the story of Czechoslovak dactylography and reminds cases, that were very close to prove this method wrong at its fragile beginning. The second chapter focuses on the present of dactylography. This chapter starts with three basic laws of dactylography, but the essence of it lies in the term "dactyloscopic evidence". The methods of revelation, analysis and preservation of dactyloscopic evidence are described here as well as their comparison. If it comes to analysis, I am trying to compare two approaches used today (holistic and numerical) and offer my opinion which one is better. Also, I am trying to answer the question, if it is possible to tell how old the dactyloscopic evidence is. The third and the last chapter...
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Wu, Hao-Min, and 吳皓民. "Development of Interior Permanent Magnet Synchronous Motor Drive with Friction Compensation and Online Mechanical Parameters Identification." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/6whrzm.
Full textAbstract:
碩士國立臺北科技大學
電機工程系
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The choice of system controller parameters directly affects the performance of the systems dynamic response. The system may lose control or reduce the dynamic response while choosing the unsuitable parameters. It not only can adjust parameters appropriately as the system state changes, but also no need to measure and check motor parameters in advance if the system is with auto-tuning. When the motor performs a forward/reverse operation, the Coulomb friction generates instantaneously at the zero-crossing point. It will cause a momentary deviation in the speed control, and this is compensated by the feedforward control, thereby eliminating this error and improving the dynamic response at the same time. The experimental system includes the digital signal processor TMS320F28335 and an interior permanent magnet synchronous motor. The initial mechanical parameters of the controller will be set to 0.2 times of the nominal value, and the S curve will be used for parameters identification. Then feedforward control and auto-tuning technology will be added to observe the dynamic response of the system. The experimental results show that the feedforward controller can effectively suppress the influence of Coulomb friction, and the dynamic response of the system is also improved after the speed controller and feedforward controller are adjusted by auto-tuning.
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KAN, MING-KAI, and 甘銘凱. "Fuzzy Control of Anti-lock Braking System for Motorcycle Using Adaptive Parameter Estimator and Road Friction Identification." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/g873ax.
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Janotová, Martina. "Daktyloskopie - historie, současnost a budoucnost." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-368832.
Full textAbstract:
1 Abstract Fingerprinting - Past, Present and Future The objective of the presented diploma thesis is to provide a comprehensive overview of findings in fingerprints area. Fingerprinting is a unique method enabling quick, inexpensive and reliable personal identification. To provide a comprehensive understanding of the presented issue, fingerprint reputation as ever-changing and continuously developing method is put into contrast with its contradictions and current problems. The first part of the thesis describes roots and genesis of the method from its beginnings in ancient realms up to date. The process of shaping of the knowledge in the field of fingerprints into a science is presented through the works of the most prominent fingerprints personalities. Despite the difficult beginnings, fingerprints finally reached the position of trustworthy and respectful area of forensic science. Due to that; the historical part follows the journey of fingerprints evidence into the police investigation and court rooms. Final point brings an attention to the establishment of fingerprinting in Czech criminal investigation. The main part of the thesis is dedicated to the practical aspect of fingerprints expertise. To provide a deep level of understanding, particular role of fingerprints in criminal investigations and its...
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Τσουκαλάς, Αθανάσιος. "Μοντελοποίηση και έλεγχος μίκρο/νάνο ρομποτικών συστημάτων." Thesis, 2012. http://hdl.handle.net/10889/5706.
Full textAbstract:
Η παρούσα διδακτορική διατριβή έχει ως κύριο αντικείμενο μελέτης την μοντελοποίηση και έλεγχο ενός μικρορομποτικού βραχίονα αναλυόμενου σε σφαιρικά πεπερασμένα στοιχεία σε περιβάλλον με εξωτερικές δυνάμεις Van Der Waals και συνυπολογίζοντας την τριβή. Τα κύρια σημεία είναι η εισαγωγή των εξωτερικών δυνάμεων στο μοντέλο του μικρορομπότ, η δημιουργία προσαρμοστικού ελέγχου για την επίτευξη ακολουθίας τροχιάς με αναγνώριση και ακύρωση των ισχυρών μεταβαλλόμενων εξωτερικών δυνάμεων, η αναγνώριση της θέσης και η αποφυγή εμποδίων σε άγνωστο περιβάλλον κλίμακας μικρομέτρων και ο καθορισμός τροχιάς για προσέγγιση σημείων στον χώρο εργασίας του μικρορομπότ. Προτείνεται επίσης ένα σύστημα επενέργησης σε διάταξη τένοντα με νανοκαλώδια και γίνεται μελέτη της αντοχής του σε σχέση με τις μέγιστες δυνάμεις-ροπές που παρουσιάζονται κατά τον έλεγχο. Για την αναγνώριση των εξωτερικών δυνάμεων δοκιμάζονται διαφορετικά είδη εκτιμητών και εξετάζεται η απόδοσή τους στο συνολικό σύστημα.The present PhD thesis has a key object the modeling and control of a micro robotic manipulator, represented by spherical particles in an environment with external Van Der Waals forces and taking friction into account. The main points are a) the insertion of the external forces in the micro robot model, b) the adaptive control used in order to follow a desired trajectory, with identification and cancellation of the external forces, the position identification and avoidance of obstacles in an unstructured micrometer scale environment and the trajectory planning towards a target point in the task space of the microrobot. Also a tendon like actuation system is proposed, using nanowires and its mechanical properties are studied in order to determine the viability of its use in relation to the required torques during the control process. For the external force identification scheme, various types of estimators are proposed and their efficiency in the system is studied.
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Bilandi, Shahram Tafazoli. "Identification of frictional effects and structural dynamics for improved control of hydraulic manipulators." Thesis, 1997. http://hdl.handle.net/2429/6805.
Full textAbstract:
Frictional terms and structural dynamics play an important role in achieving high quality
performance of hydraulic manipulators. This thesis is mainly concerned with the identification
of these effects and compensation thereof through control, for two different industrial applications.
The first application pertains to a Cartesian electrohydraulic manipulator of a prototype fish
processing machine which has been developed in the Industrial Automation Laboratory. Both modelbased
and observer-based approaches to friction estimation are investigated for this basic system. In
the first approach, a friction model is used that is linear in parameters, and the friction is assumed to
be a fixed function of velocity. The model parameters and the object mass are determined by applying
the least squares estimation procedure to experimental data. A combination of Coulomb, viscous,
and Stribeck components are observed in the identified friction model. In the second approach, a
modified version of an available nonlinear observer is used for real-time estimation of the friction
parameter. Convergence rate of the observer is analyzed and an approximate algorithm is developed
for choosing its gains. Next, a novel technique is developed for friction-compensated tracking control
of the manipulator. The technique incorporates the estimated frictional force in an acceleration
feedback control law. Specifically, the model-based approach to friction estimation results in a fixed
friction compensation algorithm and the observer-based approach to friction estimation results in an
adaptive friction compensation algorithm. Experimental investigations show that the technique that
is presented in this thesis considerably improves tracking performance of the manipulator.
The second application is a mini excavator system which is a typical example of the humanoperated
mobile hydraulic machines. A new technique is presented in this thesis for indirect
measurement of the joint torques of the backhoe links using load pin force sensors. Also, to be
able to control the link motions electronically, the original pilot stage is modified by using on/off
solenoid valves that are operated with DPWM (Differential-Pulse-Width-Modulation) current signals.
Modeling and identification of the modified pilot stage is studied in the thesis in detail. According to
the experimental results, the designed switching pilot system has a reliable performance that is linear.
After the instrumentation phase, experiments are carried out with the mini excavator to determine
the mass and inertia-related parameters of the links. To estimate the six mass-related (gravitational) parameters, sensor outputs are recorded in various static poses of the manipulator. The least squares
estimation procedure is then applied to the decoupled form of the torque equations. The validation
tests which we have carried out verify that the identified parameters can be used to estimate the
static joint torques, with a good accuracy. An efficient algorithm is then developed for real-time
estimation of the bucket load under static conditions. Experimental results show that the bucket load
can be estimated at an accuracy level of 5%. To study the structural dynamics of the system, the
Euler-Lagrange equations are derived for the manipulator. The structural (dynamic) parameters are
defined using these equations. It is shown in this thesis that the six gravitational parameters are a
subset of the nine dynamic parameters. Joint friction coefficients are then added to the parameter set.
Finally, the combination of the dynamic parameters and friction coefficients are estimated from the
identification data that is obtained by simultaneous movement of the links. The results are consistent
with those of the static experiments. In this research, it is found that the friction inside the actuator
seals is quite significant. It follows that the joint torques can be measured more accurately by using
load pins instead of pressure sensors.